The stations will be launched during Wednesday morning ceremonies at the city and town halls in Brookline, Somerville and Cambridge. The launch will be followed by a celebration in Harvard Square.

Introduced last summer, Hubway plans to launch 24 bike stations in Cambridge, 12 in Somerville and at least three in Brookline.

Boston also will get 11 more stations for a total of 72.

Under the sharing system, bikes are available for short-term rental at sidewalk vending stations throughout Boston. The program aims to make the city more bicycle friendly and reduce the reliance on cars.

The program is part of a trend of bike sharing initiatives across the country.